In internal combustion engines with an injection system, the injection time is conventionally defined as a function of the angular position of the crankshaft. However, in a four-stroke engine injection operations for a specific combustion chamber do not take place at every revolution so that in order to define the injection time it is also necessary to know the phase angle of the crankshaft. For this reason, during the starting operation of the internal combustion engine the angular position of the camshaft is conventionally also sensed in order to derive the phase angle of the crankshaft therefrom.
However, it is a disadvantage here that when the camshaft sensor fails or has a malfunction it is not possible for the internal combustion engine to operate.